1. Field of the Invention
This invention relates to improvements in check valves, and more particularly, a swing-type check valve.
2. Discussion of the Prior Art
Swing-type check valves have been known for many years and are widely used in many industrial processes for preventing the backflow of liquid through a conduit. Generally speaking, such valves have been difficult to repair, frequently requiring replacement of an entire valve body when only a portion of the structure, such as the valve seat, becomes worn through use.
In view of the fact that swing check valves are desirably designed such that the valve can be used either in a horizontally extending conduit or in a vertically extending conduit, heretofore, the valve body usually is designed such that the disc will open through an angle of less than 90.degree.. The reason being that when such a valve is used in a vertical orientation, it is necessary that the disc swing from an open position to a closed position in the event of a condition of no-flow through the conduit in which the valve is installed. In other words, the valve disc should be oriented in such a way that it will close solely by gravity in the event of a no-flow condition.
It is important in the operation of swing check valves that the hinge pin for the disc extend at 90.degree. to the axis of not only the disc, but also the seat, in order that the disc will seat evenly on the seat. In the past, valves have frequently not maintained such alignment, either through faulty assembly or wear of the hinge pin or its support. When such occurs, the disc does not become properly aligned on closure.